Recent techniques developed in this laboratory allow quantitation of red cell antibodies and also determination of the immunological specificity, thermodynamic and kinetic properties of these antibodies in serum and on the cells. The biological significance of these laboratory parameters will first be evaluated in blood group isoantibodies and subsequently in various autoimmune diseases. We have evidence suggesting that these tests improve accuracy of diagnosis in autoimmune diseases, and also are useful in determining the etiology, prognosis and selection of therapy. To achieve these goals, the following research plan is proposed: 1. The new techniques will be applied to studies of known antigen-antibody systems such as Rh, ABO, MN, Duffy, Kell, etc. These results will be correlated with known biological properties of these antibodies. These data will be used as standard references for autoimmune diseases. 2. Similar laboratory data will be obtained in various autoimmune diseases. 3. Attempts will be made to correlate these data with red cell survival times and other clinical manifestations. 4. As an animal model, similar data will be obtained in dogs afflicted with autoimmune diseases. 5. Eventually, an analog computer simulation of various organs and factors contributing to autoimmune diseases will be developed. This would allow prediction of the in vivo effects of quantitative data obtained in patients.